If you follow the directions and finish at the target volume with an extract kit you should have the correct OG. I have added slightly more water on top up and still hit the OG as near as I can read it on my hydrometer scale. Do you have a refractometer that corrects automatically for temperature? If not you are getting inaccurate readings.

My theory as to why this is happening is that perhaps I'm not getting enough LME out of the canister. Would this explain the difference?

Maybe if you were leaving LME behind. You can add some hot water to the can/jug and shake it up and pour it into your pot when you add the LME, to make sure you get it all out.

Can you check your reading next time? Take an OG reading with your hydrometer and one with your refractometer to make sure they match. My refractometer had to be "calibrated" and adjusted with a 1.0033 correction factor. Now it's dead on!

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